Aromatic fluorine-containing organotin compounds and anti-tumour composition

ABSTRACT

The invention relates to novel aromatic fluorine-containing organotin compounds of the formula {(F 5  C 6  RCO 2  SnBu 2 ) 2  O} 2  and {(F 5  C 6  RCO 2 ) 2  SnBu 2  } wherein R is CH 2 , CH═CH or a single bond between the phenyl ring and the CO 2  group, and Bu is a butyl group; as well as to anti-tumour compositions containing as an active ingredient one or more of these compounds.

This invention relates to novel aromatic fluorine-containing organotin compounds and to anti-tumour compositions containing said compounds.

DISCLOSURE OF THE PRIOR ART

The substitution of hydrogen for fluorine substantially influences the biological activity of organic molecules (J. T. Welch, Tetrahedron, 43 (1987), 3123).

Fluorine (Van der Waals radius: 1.35 Å) resembles hydrogen (Van der Waals radius: 1.20 Å) but, because of the strength of the C-F bond, the fluorine substituent is very resistant to metabolic transformations. The very high electronegativity of fluorine, however, makes it quite different from hydrogen: its presence strongly affects the electronic distribution in the molecule, i.e. its dipole moment, the basicity, acidity or reactivity of neighbouring groups, etc.

We have already synthesized several fluorine-containing organotin compounds, of which the antitumour activity was screened against two human tumour cell lines, MCF-7, a mammary tumour, and WiDR, a colon carcinoma.

The di-n-butyltin monofluorobenzoates {(4-F-C₆ H₄ CO₂ SnBu₂)₂ O}₂ and (4-F-C₆ H₄ CO₂)₂ SnBu₂ (see M. Gielen, A. El Khloufi, M. Biesemans and R. Willem, Appl. Organomet. Chem., 7 (1933), 119-125) are characterized by ID₅₀ values of 81 and 360, and 90 and 309 ng/ml, respectively, comparable to those observed for etoposide. Of the corresponding difluorobenzoates (see M. Gielen, M. Biesemans, A. El Khloufi, J. Meunier-Piret, F. Kayser and R. Willem, J. Fluorine Chem., 64 (1993), 279-291), the 2,3-difluorobenzoates {(2,3-F₂ C₆ H₃ CO₂ SnBu₂)₂ O}₂ and (2,3-F₂ C₆ H₃ CO₂)₂ SnBu₂, exhibit for instance ID₅₀ values of 9 and 120, and 23 and 283 ng/ml, respectively. This clearly shows that, at least against MCF-7, the activity is enhanced when the number of fluorine atoms of the benzoate moiety is increased. These activities are comparable to mitomycin C. The ID₅₀ values of corresponding tri- and tetrafluorobenzoates, {(2,3,6-F₃ C₆ H₃ CO₂ SnBu₂)₂ O}₂ and {(2,3,4,5-F₄ C₆ HCO₂ SnBu₂)₂ O}₂, are of the same order of magnitude: 13 and 200, and 35 and 250 ng/ml, respectively (see M. Gielen, A. El Khloufi, D. de Vos, H. J. Kolker, J. H. M. Schellens and R. Willem, Bull. Soc. Chim. Belg., 102 (1993), 761-764).

Di-n-butyltintetrafluorophthalate, F₄ C₆ -1,2-(CO₂)₂ SnB₂, (see M. Gielen, M. Bou alam, A. Meriem, B. Mahieu, M. Biesemans and R. Willem, Heteroatom Chem., 3 (1992), 449-452) is characterized by very low ID₅₀ values, especially against WiDr, viz. 51 and 68 ng/ml.

The di-n-butyltin 2-fluorocinnamates and 4-fluorophenylacetates, {(2-F-C₆ H₄ CH═CHC₂ SnBu₂)₂ O}₂ and {(4-F-C₆ H₄ CH₂ CO₂ SnBu₂)₂ O}₂ (see M. Gielen, A. El Khloufi, M. Biesemans, F. Kayser and R. Willera, Appl. Organomet. Chem., 7 (1993), 201-206) have comparable activities, i.e. ID₅₀ values of 28 and 368, and 38 and 268 ng/ml.

SUMMARY OF THE INVENTION

The present invention provides novel aromatic fluorine-containing organotin compounds of the formula {(F₅ C₆ RCO₂ SnBu₂)₂ O}₂ or {(F₅ C₆ RCO₂ SnBu)₂ } wherein R is CH₂, CH═CH or a single bond between the phenyl ring and the CO₂ group, and Bu is a butyl group.

This invention also provides anti-tumour compositions, containing as an active ingredient one or more aromatic fluorine-containing organotin compounds as defined above, and a pharmaceutically acceptable carrier.

The present compounds show a markedly better solubility in polar solvents, such as ethanol, than the above discussed tested compounds; the solubility of the present compounds in ethanol is about 10 times higher than that of the known compounds (about 50 mg/ml). Furthermore, the present compounds show activities against a broad spectrum of tumours, as appears from the experimental part disclosed hereinafter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Syntheses and purifications

The compounds 1 to 3 of the general formula {F₅ C₆ CO₂ SnBu₂)₂ O}₂, {(F₅ C₆ CH₂ CO₂ SnBu₂)₂ O}₂ and {(F₅ C₆ CH═CHCO₂ SnBu₂)₂ O}₂, were synthesized from the corresponding organic acid and di-n-butyltin oxide in a 1:1 molar ratio, and {(F₅ C₆ CH₂ CO₂)₂ SnBu₂ }, 4, was synthesized employing a 2:1 molar ratio, using the following procedure: The appropriate acid was dissolved in a 4:1 mixture of toluene and ethanol. The reacting mixture was refluxed for 4 to 6 h. The ternary azeotrope, water/ethanol/toluene, followed by the binary, azeotrope ethanol/toluene, were distilled off with a Dean-Stark funnel up to 50% reduction of the initial volume. The solvents were evaporated under reduced pressure. The solid or oil obtained was purified by recrystallization in appropriate solvents.

The following compounds were prepared:

{(F₅ C₆ CO₂ SnBu₂)₂ O})₂, compound 1

Recrystallized from ethanol/petroleum ether; mp: 151°-153° C., yield: 94%; M ossbauer parameters (in mm/s): QS: 3.68, IS: 1.42, Γ₁ & Γ₂ :1.10 & 0.98; ¹ H NMR (CDCl₃): α& β-CH₂ : m, 1.46-1.78; γ-CH₂ ; tq, 1.34 [7, 7] and tq: 1,51 [7,7]; CH₃ ;t, 0.87 [7] and t: 0.89 [7]; ¹³ C NMR (CDCl₃): C-1: td, 111.8 [4, 19]; C-2 & C-6: bd, 141.8 [253]; C-3 & C-5: bd, 137.8 [248]; C-4: bd, 144.2 [264]; CO; 164.3; α-C: 28.7 [bs] and 29.8 [bs]; β-C: 27.0 [² J(¹³ C-^(119/117) Sn): 35] and 27.3 [² J(¹³ C-^(119/117) Sn): 35]; γ-C: 26.6 [³ J(¹³ C-^(119/117) Sn): 121] and 26.7 [³ J(¹³ C-^(119/117) Sn); 123]; CH₃ 13.2 and 13.3; ¹⁹ F NMR (CFCl₃): F-2 & F-6: dddd,-141.4 [^(n) J(¹⁹ F--¹⁹ F): 21, 3, 2,-8]; F-3 & F-5: dddd, -161.2 [^(n) J(¹⁹ F--¹⁹ F): 21, 21, 3,-8]; F-4: t, -152.1 [³ J(¹⁹ F--¹⁹ F): 21]; ¹¹⁹ Sn NMR (CDCl₃):-189,5,-190.6 [² J(¹¹⁹ Sn-O-^(117/119) Sn): 126]

{(F₅ C₆ CH₂ CO₂ SnBu₂)₂ O}₂, compound 2

Recrystallized from ethanol/petroleum ether; mp: 76°-77° C., yield; 85%; M ossbauer parameters (in mm/s): QS: 3.39, IS: 1.29, Γ₁ & Γ₂ : 0.96 & 0.99; ¹ H NMR (CDCl₃): CH₂ CO: S, 3.56; α- & β-CH₂ ; m, 1.44-1.54; γ-CH₂ ; tq 1.27 [7, 7] and tq: 1,29 [7,7]; CH₃ ; t, 0.86 [7] and t: 0.89 [7]; ¹³ C NMR (CDCl₃): C-1; dt, 109.9 [17, 4]; C-2 & C-6: bd: 145.3 [247]; C-3 & C-5: bd: 137.4 [253]; C-4; bd; 140.3 [249]; CH₂ CO: 29.6; CO: 173.9; α-C: 29.5 [bs] and 29.1 [bs]; β-C: 27.2 [² J(¹³ C-^(119/117) Sn): 32] and 27.6 [² J(¹³ C-^(119/117) Sn): 37]; γ-C: 26.6 [³ J(¹³ C-^(119/117) Sn): 125] and 26.8 [b]; CH₃ : 13.2 and 13.3; ⁹ F NMR (CFCl₃): F-2 & F-6: dddd,-143.4 [^(n) J(¹⁹ F--¹⁹ F): 21, 3, 2,-9]; F-3 & F-5: bs ,-163.3; F-4: bs,-156.8; ¹¹⁹ Sn NMR (CDCl₃):-204.6,-209.3 [² J(¹¹⁹ Sn-O-^(117/119) Sn): 121]

{(F₅ C₆ CH═CHCO₂ SnBu₂)₂ O}₂, compound 3

Recrystallized from ethanol/petroleum ether; mp: 110°-112° C., yield: 93%; M ossbauer parameters (in mm/s): QS: 3.53, IS: 1.34, Γ₁ & Γ₂ : 0.98 & 0.99; ¹ H NMR (CDCl₃): α-CH: d, 6.70 [16]; β-CH: d, 7.52 [16]; α- & β-CH₂ ; m, 1.64-1.75; γ-CH₂ ; tq, 1.37 [7, 7] and tq: 1,43 [7,7]; CH₃ ; t, 0.86 [7] and t: 0.89 [7]; ¹³ C NMR (CDCl₃): C-1: td, 110.4 [4, 14]; C-2 & C-6: bd: 145.5 [254]; C-3 & C-5: bd: 137.5 [249]; C-4: bd: 1:37.9 [249]; α-CH: 130.0; β-CH: 126.9; CO: 171.4; α-CH₂ : 29.7 [bs] and 29.7 [bs]; β-CH₂ : 27.4 [² J(¹³ C-^(119/117) Sn): 36] and 27.7 [² J(¹³ C-^(119/117) Sn); 36]; γ-CH₂ : 26.6 [³ J(¹³ C-^(119/117) Sn): 121] and 26.8 [³ J(¹³ C-^(119/117) Sn); 125]; CH₃ : 13.2 and 13.3; ¹⁹ F NMR (CFCl₃): F-2 & F-6: dddd,-140.4 [^(n) J(¹⁹ -F--¹⁹ F): 21,3, 1, -8]; F-3 & F-5: dddd,-162.7 [21, 21,3,-8]; F-4: t,-152.9 [21]; ¹¹⁹ Sn NMR (CDCl₃): -206.6, -215.5 [² J(¹¹⁹ Sn-O-^(117/119) Sn): 113]

{(F₅ C₆ CH₂ CO₂)₂ SnBu₂ }, compound 4

Recrystallized from ethanol/hexane; mp: 125°-126° C., yield: 90%; M ossbauer parameters (in mm/s): QS: 3.85, IS: 1.51, Γ₁ & Γ₂ : 0.99 & 0.89; ¹ H NMR (CDCl₃): CH₂ CO: s, 3.70; α- & β-CH₂ ; m, 0.58-1.72; γ-CH₂ ; tq, 1.34 [7, 7]; CH₃ ; t, 0.88 [7]; ¹³ C NMR (CDCl₃): C-1: td, 108.7 [3, 18]; C-2 & C-6: bd: 145.3 [248]; C-3 & C-5: bd: 137.5 [253]; C-4: bd: 140.6 [253]; CH₂ CO: 27.7; CO: 178.1; α-C; 25.6 [¹ J(¹³ C-^(119/1117) Sn): 561/536]; β-C: 26.4 [² J(¹³ C-^(119/117) Sn): 35]; γ-C; 26.2 [³ J(¹³ C-^(119/117) Sn): 95]; CH₃ : 13.3; ¹⁹ F NMR (CFCl₃): F-2 & F-6: dddd, -143.1 [^(n) J(¹⁹ F--¹⁹ F): 21, 3, 1,-8]; F-3 & F-5: dddd,-162.9 [21, 21, 3,-8]; F-4: t, -156.1 [21]; ¹¹⁹ Sn NMR (CDCl₃):-131.3

The above compounds were tested in vitro against the following human tumour cell lines

MCF-7 breast cancer

EVSA-T breast cancer

WIDR colon cancer

IGROV ovarian cancer

M19 MEL melanoma

A498 renal cancer

The tests were carried out according to the method of Y. P. Kepers, P. E. Pizao, G. J. Peters, J. Van Ark-Otte, B. Winograd, H. M. Pinedo, Comparison of the sulforhodamine B protein and tetrazolium (MTT) assays for in vitro chemosensitivity testing. Eur. J. Cancer 27: 897-900; 1991.

The ID₅₀ values in mg/ml for the above for compounds and for two known compounds (carboplatin and cisplatin) were determined according to the above mentioned procedure. ID₅₀ is the amount which inhibits 50% of the cell growth. The results are shown in the following table.

    ______________________________________                                         ID.sub.50 values in mg/ml                                                      Compounds                                                                              MCF-7   EVSAT    WiDr  IGROV  M19  A498                                ______________________________________                                         1       44      39       214   53     86   76                                  2       55      43       275   60     114  105                                 3       32      37       234   41     66   135                                 4       10      19       145   20     36   51                                  Carboplatin                                                                            5500    1100     1500  780    5300 3500                                Cisplatin                                                                              800     1200     650   79     530  1200                                ______________________________________                                    

From the above results it can be seen that the present organotin compounds exhibit excellent ID₅₀ values which are considerably lower than the ID₅₀ values of the known compounds which were tested for comparative purposes. 

What is claimed is:
 1. An aromatic fluorine-containing organotin compound of the formula {(F₅ C₆ RCO₂ SnBu₂)₂ O}₂ or {(F₅ C₆ RCO₂)₂ SnBu₂)} wherein R is CH₂, CH=CH or a single bond between the phenyl ring and the CO₂ group, and Bu is a butyl group.
 2. An anti-tumour composition, containing as an active ingredient one or more aromatic fluorine-containing organotin compounds of the formula {(F₅ C₆ RCO₂ SnBu₂)₂ O}₂ or {(F₅ C₆ RCO₂)₂ SnBu₂ } wherein R and Bu have the meanings defined in claim 1, and a pharmaceutically acceptable carrier.
 3. A process of preparing an aromatic fluorine-containing organotin compound of the formula {(F₅ C₆ RCO₂ SnBu₂)₂ O}₂ or {(F₅ C₆ RCO₂)₂ SnBu₂ } wherein R is CH₂, CH═CH or a single bond between the phenyl ring and the CO₂ group, and Bu is a butyl group, by reacting the corresponding acid with di-n-butyltin in a molar ratio of from 1:1 to about 2:1 under reflux conditions in a suitable solvent, followed by removal of the solvent to obtain the desired compound. 